This invention relates in general to linear actuators that are adapted to cause linear reciprocating movement of a workpiece along a desired path. In particular, this invention relates to an improved structure for such a linear actuator that is relatively compact in size, inexpensive in construction, and yet which is capable of handling relatively heavy loads.
A linear actuator is a device which is used to cause linear movement, typically reciprocating linear movement, of a workpiece along a desired path of movement. A typical linear actuator includes an electric motor having a rotatable output shaft. The output shaft of the electric motor is connected through a gear train to a nut and lead screw mechanism. Rotation of the output shaft of the electric motor causes corresponding rotation of the lead screw. The nut has an opening formed therethrough having an internal thread. The lead screw extends through the opening and has an external thread formed which cooperates with the internal thread formed on the nut. The nut is mounted on the lead screw in such a manner as to be restrained from rotating with the lead screw when the lead screw rotates. As a result, rotation of the lead screw causes linear movement of the nut axially along the lead screw. The direction of such axial movement of the nut (and the workpiece connected thereto) is dependent upon the direction of rotation of the lead screw.
Linear actuators are widely used in a variety of applications ranging from small to heavy loads. To accommodate heavy loads, known linear actuator structures have been formed from relatively large and heavy metallic components. Consequently, linear actuator structures currently in use are relatively heavy and expensive. Thus, it would be desirable to provide an improved linear actuator structure which is relatively lightweight and inexpensive to produce, and yet which is capable of handling heavy loads.